Guhring 9039770381000 Spiral Flute Tap 1-1/2-6 Unc Cobalt

Product Description

The GUHRING 9039770381000 is a spiral flute bottoming tap designed for right-hand internal threading in blind holes. Built from cobalt high-speed steel with a TiN (titanium nitride) coating, this tap handles alloyed and unalloyed steel with consistent tool life. It cuts a 1-1/2-6 UNC thread to a 2B class of fit with an H7/H8 thread limit, producing accurate, clean threads in production or maintenance environments. The 6-flute fast-helix design at 40 degrees drives chips up and out of the hole efficiently. Overall length is 6.378 inches. Licensed machinists and toolroom technicians are the primary users of this tool.

This tap is suited for blind hole threading applications in ferrous materials, specifically alloyed steel and unalloyed steel. The bottoming chamfer geometry allows threading close to the bottom of a blind hole, making it the right choice when full thread depth is required with minimal runout at the end of the bore. The Series 3977 designation places it within a professional-grade tooling family from GUHRING. It is used in CNC machining centers, turret lathes, and manual tapping operations where repeatable thread quality is required.

Key Features

• Bottoming chamfer for maximum thread depth in blind holes
• 6-flute fast spiral at 40-degree helix angle for efficient chip evacuation
• Cobalt HSS construction for heat and wear resistance in steel applications
• TiN coating reduces friction and extends tool life
• H7/H8 thread limit for 2B class of fit compliance
• No coolant-through design — suitable for flooded or manual lubrication setups

Compatibility

Designed for threading 1-1/2-6 UNC blind holes in alloyed steel and unalloyed steel. Fits standard tap holders and chucks accepting a 1.233-inch shank diameter with a 0.925-inch square drive.

Installation Notes

This tap should be installed and operated by qualified machinists familiar with tapping speeds, cutting fluid selection, and torque limits for large-diameter taps. Always secure the workpiece and verify spindle alignment before engaging the tap to avoid tap breakage or thread distortion. Apply appropriate cutting fluid rated for steel — dry tapping is not recommended at this diameter. Follow shop floor procedures and machine manufacturer guidelines for tapping cycle parameters.